Film-perforating device

ABSTRACT

A ROTARY FILM-PREFORATIN DEVICE IS PROVIDED WITH A PLURALITY OF NICHROME OR OTHER METALLIC NEEDLES WHICH ARE ELECTRICALLY HEATED BY CURRENT FLOWING THROUGH THE NEEDLES SO THAT THE HETING EFFECT IS CONCENTRATED IN THE NEEDLEW WHICH PERFORM THE PREFORATING OPERATION.

Nov.9,1971 s. ZELNICK 3,618,439

\ FILM-PERFORA'IING DEVICE I Filed June 1. 1970 2 sham-sheet 1 FIG.|

INVENTOR SEYMOUR ZELANICK ATTORNEY Nov. 9, 1971 s. ZELNICK 3,613,439

' FILM-PERFORATING DEVICE Filed June 1, 1970 2 Sheets-Shoot 2 [IE HE INVENTOR SEYMOUR ZELNICK IOD 1 D BY w (1 M (Q L.

FIG.4

ATTORNEY 3,618,439 Patented Nov. 9, 1971 3,618,439 FILM-PERFORATING DEVICE Seymour Zelnick, Orange, N.J., assi'gnor to Weldotron Corporation, Newark, NJ. Filed June 1, 1970, Ser. No. 42,227 Int. Cl. B26d 7/10 U.S. Cl. 83-171 10 Claims ABSTRACT OF THE DISCLOSURE A rotaryfilm-perforating device is provided with a plurality of Nichrome or other metallic needles which are electrically heated by current flowing through the needles so that the heating effect is concentrated in the needles which perform the perforating operation.

BACKGROUND OF THE INVENTION (1) Field of the invention This invention relates to means for perforating plastic film on a continuous basis for various purposes, for example:

(1) In the shrink packaging industry perforations are used to permit entrapped air to escape as the envelope of film shrinks, thus preventing Ballooning.

(2) Perforations are used to create easy-opening or tear-strip effects.

(3) Perforations can be used to effect simple separation of a continuous string of packages. See my assignees US. Pat. No. 3,357,151.

(4) Perforations can be used to impart a breathing quality to plastic film.

(2) Description of the prior art The conventional method for continuously perforating plastic film involves the use of an array of rotating needles, either heated or unheated. The use of unheated needles is quite critical and often results in film tearing or in the formation of perforated holes which can readily propagate tears in subsequent processing or use of the film.

The use of heated needles has the advantage that a melting action occurs around the perimeter of the perforated hole resulting in a reinforced edge which is greatly resistant to tear propagation. The common method for heating the needles is to embed them in a heated cylinder and then depend on heat conduction from the cylinder to the points of the needles to produce the desired effect. This method has the following disadvantages:

(1) It requires the heating of a relatively large mass (the cylinder) to produce a heating effect on a very small mass (the needles).

(2) The effect of the large heated mass in close proximity to the film produces undesirable heating effects on those areas where no heat is desired.

(3) There is a relatively low practical upper limit to which the needles can be raised in temperature by this technique (4'00 -50 F.).

SUMMARY OF THE INVENTION The primary object of this invention is to obviate the above mentioned disadvantages and to provide certain desirable features which will presently become apparent. In brief, my device consists of an array of nichrome (or similar alloy) elements mounted along the periphery of two electrically isolated conductive discs which can be connected to opposite polarity potentials by means of brushes. By this means a current can be made to flow through the Nichrome elements and by varying the magnitude of the current the elements can be heated to almost any desired degree varying from lukewarm to incandescence. Thus, the heating effect is concentrated in the Nichrome elements which are the actual perforating devices.

The parameters which determine the shape and size of the perforated hole are the shape of the Nichrome wire (which is easily varied) and the temperature of the Nichrome wire, which not only can easily be varied but can 'be rapidly varied even while the unit is in operation. Thus, a unique characteristic of this design is that hole size can be readily and rapidly varied While the unit is in continuous operation.

BRIEF DESCRIPTION OF THE DRAWING The above and other objects, features and advantages of the invention will be apparent from the following speci- :fication considered in connection with the accompanying illustrative drawings of the presently preferred embodiment of the invention. In the drawings:

FIG. 1 is a view in elevation and partly in section of a rotary film-perforating device of the invention;

FIG. 2' is a sectional view on the line 2-2 of FIG. 1;

FIGS. 3 and 4 show needle arrangements which may be used in the device of FIG. 1 in lieu of the needle arrangement of FIG. 1, and

FIGS. 5 and 6 show a slotting device which can be used in the device of FIG. 1 in place of the needles DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION The nichrome or other metallic film-perforating elements 10 have portions 12 which are secured in recesses 14, by screws or plugs 16 or in any other suitable way, in electrically conductive rotary member shown as discs 18 of brass or other electrically conductive material. Each of said elements has a free end portion and two devergent portions 12 secured respectively in said recesses in a pair of said discs. It will be understood that a plurality of elements 10 are carried by said discs in circumferentially spaced relation (FIG. 2). Said discs are insulated from each other by member 20 of insulation material and are insulated from shaft 22 by bushings 24 of insulation material. Said discs are secured to member 20 by screws 26 and the assembly is locked to the shaft by collars 28 secured to the shaft.

The perforating elements 10 are energized from the variable voltage source 30 to which they are coupled by the brushes 32 which bear on the peripheries respectively of discs 18.

The film 34 is fed by the driven rubber covered roller 36 and by the rubber covered rollers 38 which clamp the film aaginst roller 36. Rollers 38 are secured to shaft 22 by collars 40 secured to said rollers and to said shaft. Thus the perforating elements 10 are caused to rotate at the same surface speed as that of the film, since the rollers 38 impart the driving motion to the shaft 22. Shaft 36 has a circular groove 42 providing clearance for the elements :10.

In addition to a basic perforator as shown, the great flexibility of this technique permits many variations. Thus, simply by changing the shape of the Nichrome elements, two lines of perforations may be produced, as shown in FIG. 3. Or, by paralleling similar sections, entire zones of perforations may be produced, as shown in FIG. 4. FIG. 3 shows the needles 10A, provided with two filmpenetrating end portions 10B and 10C, carried by the brass discs 18A which are insulated from each other by member 20A. The Way the arrangement shown by FIG. 3 can be used in the device shown by FIG. 1 is obvious, it being merely required that the assembly comprising the parts 18, 20 be replaced by the assembly of FIG. 3. The

3 arrangement illustrated by FIG. 4 is obvious, the needles being indicated at D, the metal discs at 1 8D, and the insulations at D. The assembly shown by FIG. 4 can thus replace the assembly comprising the parts 1 8, 20 in FIG. 1.

Another type of perforation can be provided by the arrangement illustrated by FIGS. 5 and 6. As here shown the perforating elements 11B are disposed parallel to the plane of the discs 18E, the insulation member being indicated at 20E. By the use of this arrangement, the film is provided with narrow longitudinal slots. This device can replace parts 18, 20 of FIG. 1.

While the device has been illustrated as being used to perforate a single web of film, it can also be used to perforate one layer of a double web of 'film by introducing a thin Teflon separator between the two layers.

While there have been shown and described preferred embodiments of the invention, it will be understood that the invention may be embodied otherwise than as herein specifically illustrated or described, and that in the illustrated embodiments certain changes in the details of construction and in the form and arrangement of the parts may be made without departing from the underlying idea and principles of this invention within the scope of the appended claims.

What I claim is:

1. A film-perforating device comprising a plurality of electrically conductive rotary members, insulated from each other and arranged in at least one pair, said electrically conductive rotary members are driven by a rotary shaft electrically insulated from said rotary members, a plurality of electrically conductive film-perforating members carried by a pair of said electrically conductive rotary members in circumferentially spaced relation and projecting radially from said rotary members, each of said film-perforating members being in electrical contact with said pair of rotary members, and stationary electrical contact members having a brushing contact with said electrically conductive rotary members for coupling said perforating members to a voltage source for the flow of electric current through said perforating members to heat them.

2. A film-perforating device. according to claim 1, including film-feeding means operable in timed relation to the surface speed of said rotary members for presenting the film to said perforating members in succession.

3. A film-perforating device according to claim 1, including film-feeding means operable in timed relation to the surface speed of said rotary members for presenting the film to said perforating members in succession, said film-feeding comprising a rubber covered roller and a pair of rollers of larger diameter than said first mentioned roller and secured to said shaft in longitudinally spaced relation and cooperating with said first mentioned roller in clamping relation to said film whereby the sur- 4 face speed of said rotary members is the same as the film speed.

4. A film-perforating device according to claim 1, wherein each of the perforating member comprises a plurality of film-penetrating end portions.

5. A film-perforating device according to claim 1, wherein a series of pairs of the rotary members are carried by the shaft with an insulating member between each pair.

6. A film-perforating device according to claim 1, wherein each of the film-perforating members is formed of Nichrome wire or the like.

7. A film-perforating device according to claim 1, wherein each of said perforating members has a needlelike free end portion disposed radially outwardly of said rotary members and two diverging parts secured respectively to two of the rotary members.

8. A film-perforating device according to claim 1, wherein said film-perforating members have circumferentially extending portions disposed outwardly of said r0- tary members, respectively, in positions parallel to the sides of the latter.

9. A film-perforating device according to claim 1, wherein said contact members brushingly engage the periphery of said rotary members, respectively, clear of the connections of said perforating members to said rotary members, respectively.

10. A film-perforating device according to claim 1 wherein an intermediate insulation member is mounted on said shaft between a pair of the electrically conductive rotary members, a pair of insulation members mounted on said shaft and rotatable thereby, said rotary members being mounted on said pair of insulation members, and means securing said pair of insulation members to said rotary members and to said intermediate insulation members for rotation as a unit.

\ References Cited UNITED STATES PATENTS 3,244,043 5/1966 Iore et .al. 156-515 X 3,054,441 9/1962 Gex et al. 156-515 3,368,930 2/1968 Beason 156-515 X 2,464,718 3/1949 Potter et al. 83-171 3,115,564 12/1963 Stacy 156-515 X 3,216,880 11/1965 Herrington et al. 156-515 2,677,747 5/1954 Jaye 83-16 2,748,863 6/1956 Benton 83-171 3,357,151 12/ 1967 Monaghan 53-28 VOLODYMYR Y. MAYEWSKY, Primary Examiner US. Cl. X.R. 

